The transmittal of video data over a video channel in modern digital audio/video interface systems is generally subject to some storage and transmission limitations, e.g., network bandwidth. New television and video formats are being developed to provide high resolution video content. However, such development presents a new challenge to audio/video interface standards because support for high data rates is required. Video compression tools (also referred to as “video codecs”), e.g., encoders and decoders, are often used in audio/video interface standards to reduce data rate transmitted over an audio/video channel by compressing the signals of the video data.
Another data reduction technique is to reduce resolution for chroma (or color) information than for luma (or brightness) information of signals of the video data through chroma subsampling. Examples of chroma subsampling include 4:2:2 and 4:2:0 in YCbCr color space. Chroma subsampling uses fewer bits for encoding the signals of video data than for signals of video data with full chroma resolution (e.g., 4:4:4 sampling ratio), which makes the transmittal of video data more efficient while maintaining acceptable visual quality. However, encoding processes of existing video compression codecs often only accept signals of video data at full resolution (e.g., 4:4:4 sampling ratio); in other words, if a video signal uses other sampling ratios, e.g., 4:2:2 or 4:2:0, it must be converted to 4:4:4 before encoding, which may add computational complexity and performance delay.